Constant current transformer



June 5, 1928. 1,672,669

- T. G. WHYTE CONSTANT CURRENT TRANSFORMER Filed Aug. 15, 1925 Inventor":

Thomas G.Whyte,

, His Attorney.

Patented June 5, 1928.

UNITED STATES 1,672,669 PATENT OFFICE.

THOMAS G. 'WBYTE, OF LYNN, MASSACHUSETTS, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

consume CURRENT rnansronmna.

Application iiled August 13, 1925. Serial No. 50,080.

My invention relates to constant current transformers of the movable coil type in which automatic movement or displacement of the movable coils maintains the current at constant value. In some cases, the horizontal dimensions of a transformer are limited and this is particularly true in the case of a subway or manhole transformer which must be small enough horizontally to pass through the manhole opening. Thus, the size and, therefore, the capacity of the usual constant current transformer comprising a single pair of primary and secondary coils is limited under such conditions.

' Transformers have been built comprising a core of increased height with two pairs of primary and secondary coils, thus giving increased capacity without increased horizontal dimensions, and the general object of the present invention is to provide an improved transformer of this general construction.

Other objects and advantages will appear from the following description taken in connection with the accompanying drawing, in

which Fig. 1 is a perspective view of a transformer constructed in accordance with the invention, and Figs. 2, 3, 4 and 5 are diagrammatic views of several ways in which the transformer 'coils may be connected to the supply and load circuits.

Like reference characters indicate similar parts in the different figures of the drawing.

In the particular transformer shown in Fig. 1, the core is formed with an upper section and a lower section secured together to form a unit. The building of the core in two sections instead of integrally is merely to facilitate assembly and does not appreciably affect its function as a core. This core 10 comprises three vertical legs 11. 12 and 13 joined by a top yoke 14 and a bottom yoke 15 and with cross members 16 connecting the centers of the two outside legs 11 and 13 to the center of the central leg 12. The central leg 12 is the winding leg, its upper partabove the cross members 16 being surrounded by a primary coil'17 and a secondary coil 18 and its lower part below the cross member 16 being similarly provided with a second primary coil 19 and a secondary coil 20. The two lower coils 17 and 19 are fixed in position on the core. The upper coils 18 and 20, however, are mounted in frames 21 which are pivoted at the outer ends of brackets 22 extending from one side of the core. These coil structures including the coils 18 and and the frames 21 are thus free to move vertically along the winding leg 12 of the core under the combined influence of gravity and the repulsion between the primary and secondary coils. The coils may be connected to the supply circuit 23 and the load circuit 24 in a variety of ways, some of which are indicated in Figs. 2, 3, 4 and 5. The primary coils may be connected in multiple as in Figs. 2 and 3 or in series as in Figs. 4 and 5. The secondary coils may be connected in series with a single load circuit as in Figs. 2 and 4. or in series with two load circuits as in Figs. 3 and 5. ()ther connections may be used if desired.

The movable coil structures including the coils 18 and 20 are connected together by a rigid rod 25 so that these coils are always equally displaced with res ect to the two primary coils 17 and 19. T e rod 25 is provided with a turnbuckle 26 to permit accurate adjustment of the distance between the two movable coils 18 and 20.

The movable 'coil structures are connected by a rod 27 to one end of a lever 28 pivotally supported near its center at the top of the core 10, the opposite end of the lever 28 carrying weights 29 which may be varied in amount to give proper regulation of. the transformer. The length of the rod 27 may b adjusted by a turnbuckle 30 to adjust the limits of travel of the lever 28. This adjustment is of importance in the regulation of the transformer because the effect ofthe weight-s 29 varies with the angular position of the lever.

The type of transformer which has been described is commonly immersed in oil for insulating and cooling purposes and the end of the lever 28 which carries the weights 29 is bent or deflected downwardly to decrease the amount. of oil necessary to submerge the lever and weights completel at all times. is highly desirable in order that the buoyancy of the oil may remain constant and. unchanged for all positions of the lever andv weights.

Complete immersion at all amas- The movable upper coil of each pair of coils has been shown as a secondary coil because the secondary current is usually smaller than the primary current in this type of transformer and the secondary coil leads may therefore be smaller and more flexible than the rimary leads and for this reason more suita le for connection to movable coils. The connections to the coils may obviously be reversed, however, if desired.

What I claim as new and desire to secure by Letters Patent of the United States, is: A constant current transformer including a core having a vertical winding leg, a pair of coils surrounding the lower part of said winding leg, a pair of coils surrounding the upper part of said windin leg, the lower coil of each pair being fixed in position on said winding leg, means at one side of the core for pivotally supporting the upper coil of each pair to move along said winding leg, a weighted lever, rigid means connecting said movable coils together, and mains connecting said movable coils to one end of said weighted lever.

In witness whereof, I have hereunto set my hand this eleventh day of August, 1925.

THOMAS G. WHYTE. 

